The broad, long-term objective is to evaluate how osteoblast response is mediated by nutrient transport provided by dissolving amorphous calcium phosphate (ACP) particulates. We hypothesize that the attraction of ACP lies in its higher dissolution rate, and its ready interaction with osteoblasts leading to more rapid mineralization. We propose that ACP mineral immobilized membranes could be the first step in creating viable scaffolds for structural repair and regeneration. The proposed effort is distributed among three linked Aims. Aim 1 will perform targeted cell culture studies of stabilized forms of ACP both separated by neighboring osteoblasts through a membrane in the Transwell plate and by direct contact experiments under cell culture conditions between cells and ACP. We will evaluate the release rate of target ions in solution and track cell viability and function with incubation time in growth media deprived of calcium phosphate. Protein expression will be evaluated by Northern blot and other gel and assay techniques. Aim 2 will construct model porous scaffolds incorporating and immobilizing stabilized ACP within them by a photopolymerizable pre-polymer dispersion. Aim 3 will evaluate osteoblast cell response to the immobilized ACP composites from cell culture using Transwell plates to compare cell viability and function in this different mode. Similar assays are planned in Aim 3 as in Aim 1 with the distinction that other controls will be required to separate the matrix effect from the mineral effect. Thus Aim 3 leverages off of the experience gained in cell culture during Aim 1 with the ability to fabricate mineral immobilized membrane matrices in Aim 2. At the end of the project, we will have compiled strong evidence linking ACP solubility, neighboring osteoblast viability, and tissue growth and proliferation. We believe that these foundation elements will provide the basis for a successful R-01 proposal concept to be submitted as this project is completed.